Hello. I'm not sure when this happened, but I think it happened when I upgraded from gnome 2.4 to 2.6, a lot of themes got lost... it looks like the pixmaps are gone, all those theme are very.. square-like.
These include Amaranth, Lush, Wasp, Nuvola etc.
Some PKGBUILDs: http://members.lycos.co.uk/sweiss3
Have you updated gtk-engines accordingly.